Process for dimerization or co-dimerization of {60 olefin

ABSTRACT

A process in which an Alpha -olefin is dimerized or codimerized in the presence of a ternary catalyst consisting of (a) an alkyl-aluminum compound, (b) at least one titanate selected from the group consisting of the tetra-alkyl-titanates or tetraphenyl-titanates and (c) an organic phosphorus compound is disclosed.

United States Patent Yamada et al.

[ 51 Aug. 22, 1972 [54] PROCESS FOR DIMERIZATION OR CO-DIMERIZATION OF a-OLEFIN [72] Inventors: Isao Ono; Shizuo Yaniada, ii iroyuki I Abe; Kazuo Tago; Nobuko Kunihiro, all of No. 4560, Oaza-Tonda, Nanyo-cho, Tasuno-gun Yamaguchi,

[22] Filed: June 1, 1970 [21] Appl. No.: 42,590

[30] Foreign Application Priority Data May 29, 1969 Japan. ..44/420l2 Jan. 14, 1970 Japan ..45/3990 [52] US. Cl..260/683.l5 D, 252/431 P, 260/949 CB [51] Int. Cl ..C07c 3/10 [58] Field of Search ..260/683. 15 D Primary Examiner-Paul M. Coughlan, Jr. Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak ABSTRACT A process in which an a-olefin is dimerized or C0- dimerized in the presence of a ternary catalyst consisting of (a) an alkyl-aluminum compound, (b) at least one titanate selected from the group consisting of the tetra-alkyl-titanates or tetra-phenyl-titanates and (c) an organic phosphorus compound is disclosed.

13 Claims, No Drawings PROCESS FOR DIMERIZATION OR CO- DIMERIZATION OF aOLEFIN BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to a method of dimerization or co-dimerization of a-olefin. More particularly, this invention relates to a method of dimerization or codimerization of a-olefins.

2. Description of the Prior art Hitherto, numerous research on synthesing n-butene has been done, particularly in the production of n-butene by dimerizing ethylene; a considerable number of patents and reports are known. However, a method of dimerization has not been established.

n the other hand, a-olefins having five to six carbons, including 3-methyl-butene-l and 4-methyl-pentene-l, are industrially useful derivatives, and accordingly numerous studies in the field of dimerization or co-dimerazation of ethylene, propylene and n-butene are reported. However, olefins with many carbon atoms have many isomers, and the dimers or the codimers formed often contain isomers. Presently, a process for the selective synthesis of a-olefins by dimerization or co-dimerization is not available.

In these circumstances, the present invention made a search for catalyst for dimerizing or co-dimerizing aolefin including dimerization catalyst of ethylene.

But, as has already been mentioned in preceding Japanese Patent 5067/57, a small quantity of solid polymer forms in the dimerization of ethylene in spite of good catalytic activity and selectivity. It is reported that such solid polymer may hinder continuous dimerization.

Polymers formed in a dimerization process are a fibrous substance of small bulk density which will wrap in catalyst liquid, prevent its contact with ethylene and may result in reducing its catalytic activity. Also, it is considered that the formation of solid polymer will make operating for a long period of time impossible. Moreover, the formation of solid polymer is undesirable in dimerizing or co-dimerizing other a-olefins.

SUMMARY OF THE INVENTION After laborious research, the inventors have found a catalyst system having conspicuous characteristics which will initiate the dimerization of ethylene relatively readily under moderate conditions and moreover having selectivity for l-butene, and having the ability for suppressing the formation of solid polymers. MOreover, in case of dimerization or co-dimerization of other a-olefms, these catalysts are capable of suppressing the formation of solid polymers.

The method of dimerization or co-dimerization of aolefins comprises contacting an a-olefin with a ternary catalyst consisting of (A) at least one alkyl-aluminum compound selected from the group consisting of R Al and R AlH wherein R is an alkyl radical, (B) at least one titanate selected from the group consisting of Ti(OAr), and Ti(OR') wherein Ar is an aryl radical and R is a lower alkyl radical, and (C) at least one organic phosphorus compound selected from the group consisting of (R Z)(R Z)(R Z)P, R R R P and mixtures thereof wherein each of R, R and R is selected from the group consisting of a hydrogen atom, an alkyl, an aryl, and alkyl-aryl, an aralkyl radical, and derivatives thereof, and wherein Z is selected from the group consisting of oxygen and sulfur atoms.

DETAILED DESCRIPTION OF THE INVENTION In one embodiment of the invention, ternary constituents (A), (B) and (C) are an alkyl-aluminum compound (A), at least one titanate selected from the group consisting of tetra-alkyl-titanates and tetra-aryltitanates (B), and an organic phosphorus compound (C), respectively. To the catalysts obtained by contacting the ternary components, either directly or in the presence of a suitable solvent, at ordinary temperatures or below C under atmosphere pressure, or at reduced pressure, ethylene or propylene or a gas mixture of ethylene-propylene are brought into contact to effect the dimerization or the co-dimerization to produce n-butene, in particular, l-butene selectively. In this case, it is characteristic that the polymer formed during the dimerization reaction is of the high bulk density type suspended in the catalyst liquid, and does not get wrapped in the liquid. In addition, the amount of polymer fonnation is very small.

The alkyl-aluminum compounds used as the (A) constituent are compounds represented by the general formula RqAl or R,A1H, wherein R is an alkyl radical having from two to six carbon atoms in which an aluminum atom and organic carbon atoms are combined in a molecule.

The tetra alkyl-titanates or tetra-aryl-titanates used as the (B) constituent are compounds represented by a formula Ti(OR) wherein R is a lower alkyl radical having from one to eight carbon atoms, or Ti(0Ar).,, wherein Ar is a phenyl radical or a substituted phenyl radical and wherein the substituted phenyl radical is an alkyl phenyl, a halogenated phenyl, a nitrophenyl, an aryl phenyl or one of their derivatives respectively. These compounds can by synthesized by the method disclosed by Yoshino, J. Chem. Soc. of Japan Ind. Sec.,60,1,l24-l,l25, (1957).

The organic phosphorus compounds used as the (c) constituent are phosphite type compounds, represented by the general formula (R Z)(R Z) (R Z)P, or phosphine type compounds, represented by the general formula R R R P, wherein each of R, R and R in both formulas is a hydrogen atom or an alkyl, an aryl, an alkyl-aryl or an aralkyl radical or one of their derivatives, and Z is oxygen or sulfur atom.

More specifically, suitable examples of organic phosphorus compounds used as the (C) constituent are trimethyl phosphite, triethyl phosphite, triisopropyl phosphite, tributyl phosphite, tridecyl phosphite, triphenyl phosphite, tricresyl phosphite, dilaurylphenyl phosphite, diphenyldecyl phosphite, trilauryl-trithio phosphite, 2phosphite, phenyl-dilauryl-dithio phosphite, diphenyl-hydrogen phosphite, dibutyl-hydrogen phosphite, as phosphite compounds, and/or triphenyl phosphine, tricresyl phosphine, trioctyl phosphine, as phosphine compounds. Also, as alkyl ester types or aryl ester types of phosphine compounds, monethyldiethoxy phosphine, phenyl-diethoxy phosphine, etc., can be obviously used.

Further, the constituents (A), (B), and (C) are not limited to the use of one constituent, but, if desired, two or more of them can be used as a mixture which is to be considered within the scope of this invention.

be as desired, but in the case ofa (C)/(B) less than 0.1,

formation of solid polymers can be suppressed, while in the case of a (C)/(B) greater than 20, though suppression of polymer formation is sufficiently possible, the dimerization or co-dimerization activity does not particularly increase.

Next, as for concentration of the catalyst, 1 m. mol of the titanium compound per liter or higher is suitable. If 2 the concentration is less than 1 m. mol/1 deactivation of the catalyst occurs and the reproducibility of dimerization or co-dimerization decreases rapidly.

'Although the reaction of a-olefin can proceed at from -l to 150 C at the lower temperatures, the reaction velocity is so low that it is not practical, and at higher temperatures, due to the dimerization of the catalyst system, they display less activity. The preferable reaction temperature is in the range of from 30 to 80 C.

Moreover, suitable solvents such as aliphatic, aromatic and alicyclic hydrocarbons, such as heptane, toluene and cycle-hexane can be used. The reaction proceeds either at reduced pressure or at atmospheric pressure. Especially at reduced pressure, the formation of dimers or co-dimers increases.

The catalytic system used in this invention, as is demonstrated in the following examples, has comparatively high activity, and at the same time, the selectivity of the a-olefin is fairly good. In particular, the formation of l-butene in the n-butene process is very high. Moreover, the addition of the organic phosphorous compound will enhance the dimerization or cophosphorus compound. In the case of dimerization or co-dimerization of an a-olefin with other catalytic systems, the content of the a-olefins in the final products is less than several per cent in many cases. At

present the theoretical explanation of the effect of the added organic phosphorus compounds is not understood.

In the following, the invention is explained further by reference to the following examples, but this invention 0 is in no way to be limited thereby.

The catalyst was prepared in a 200 ml autoclave with an electromagnetic stirrer in a nitrogen filled dry box.

08 m. mol of the titanium compound shown in Table l was weighed in, and a calculated quantity of an n-hepstane solution of the alkyl-aluminum shown in Table l was added, then a calculated quantity of the organic i'phosphorous compound shown in Table 1 was added. jN-heptane was further added until the total volume reached 80 ml. The three component catalyst system thus obtained was ripened for minutes at the reaction temperature and then ethylene was added. The system was kept at a constant pressure, and the reaction was carried out for a definite period of time. After that, the autoclave was cooled to a temperature of -60 C and the products in the reaction vessel were discharged through a trap previously cooled with a carbon dioxide methanol solution. Further, by heating the reaction solution, the low-boiling substances consisting mainly of n-butene were collected in the same :trap.

High boiling substances consisting mainly of hexene in the reaction solution were respectively separated, and analyzed by means of gas chromatography. Further solid polymers were washed with hydrochloric methanol solution, dried and weighed. The results are shown in Table 1 below.

ourses; EXAMPLES -2- Using the same process as described in Examples 1 dimerization activity and reduce the formation of 21, the results of the reaction of ethylene with a polymers, which is a characteristic advantage in concatalyst consisting of alkyl aluminum and titanium compounds are shown in the same way in Table 1.

TABLE 1 Pres- Bu- Alkyl Titanium Organic sure tene Ex. aluminum compound phosphorus Al/Ti P/Ti Kg/ Temp. Time (note Poly- No. compound (note 1) compound ratio ratio cmG "C min. 2)g merg 1 Elm] p-Bu'PhTi (EtO),P 5.5 0.5 15 0 30 5.1 0.04 2 Et Al p-Me PhTi (1210),? 5.5 0.5 5 30 30 5.0 0.08 3 Etml H p-Am PhTi (El0)sP 15.0 7.0 15 30 38.0 0.10 4 Et AI p-Bu'PhTi (MeOhP 7.4 4.0 15 60 30 23.2 0.02 5 Et Al p-BuPhTi (EtOhP 7.4 4.0 15 I 60 30 40.9 0.05 6 EhAl p-BuPhTi (EtOhP 8.2 4.0 15 60 40 54.1 0.07 7 Et Al p-BuPhTi (EtOhP 8.2 6.0 15 60 40 58.6 0.05 8 Et Al p-AmPhTi (PrO),P 7.4 4.0 15 60 30 39.3 0.14 9 Et Al p-Am'PhTi (B u"O) P 7.4 4.0 15 60 30 42.6 0.07 10 Et Al p-Me PhTi (Decyl-OMP 7.4 4.0 15 60 30 53.4 0.09! 11 EtgAl p-Bu'PhTi (PhO) P 6.5 1.0 15 60 40 38.0 0.49 12 PrgAl m-Bu'PhTi (PhO) P(O&Decy1) 7.3 3.0 15 60 30 18.0 0.12

13 (Cal-1 9 A] p-Bu'PhTi (Ph0)P (O-L8U 'yl)z 7.4 4.0 15 30 25.0 0.08 14 EQAI p-Bu'PhTi (C H SLP 5.5 0.5 15 60 30 21.0 0.23 15 Et Al p-BuPhTi (ZEt-Hexyl-OhP 6.0 2.0 10 40 30 10.5 0.l0*l 16 Et Al p-Bu'PhTi cnnnshwoph 5.0 K5 "15""70 30 20.0 0.15 17 EtgAl p-BuPhTi (Oleyl-O) P 6.0 2.0 25 60 30 51.2 0.05 18 EtiAl p-BuPhTi 113091 0011 WM 5.5 0.5 15 6 0 30 25.9 0.28*2 19 Et Al p-BuPhTi (PhOhLIfQ I-l 5.5 0.5 15 60 30 21.1 0.42 20 ,Et Al p-Bu' PhTi Ph P 15:9 .9. L5 60 -39.. 30.9 21 EtaAl p-BuPhTi EtP(OEt)= 7.4 4.0 15 60 30 35.0 0.90

5 6 Comparative Example 1 Et Al p-Bu PhTi 5.5 i 60 30 21.3 3.12

Comparative Example 2 V Et Al p-Bu' PhTi 4.5 g 1s 60 30 an 1.20

(Note 1): (Oleyl-O) P: Trioleyl Phosphite Titanium compound: 0.78 0.82 m. mol was used. (Bu'O),POl-l: Di-n-butyl Phosphite (Note 2) (PhO),POl-l: Di-phenyl Phosphite The content of l-butene in the formed n-butene is Ph P: Triphenyl Phosphine over 99 percent. I EtP( OEt) Monoethyl Diethoxy Phosphine H. A ES. 1 Z '1: (A) component added after the addition of component (B) to com- In the same manner as described in Examples 1 -2 l Wmmc) the catalyst solution was charged into the autoclave. 2: (B) component added after the addition of component (A) to com- 1 5 o pone, (Q The autoclave was cooled to a temperature of 0 C and The alkyl aluminum compounds, i i into it propylene was added. Then the autoclave was pounds and organic phosphorus compounds d placed in a water bath maintained at the reaction temrespond to the following compounds respectively. perature and was left a prescribed period of time to l. Alkyl Aluminum Compounds. complete the reaction. After the reaction was Et Al: Triethyl Aluminum completed, unreacted propylene and dimers were Et AIH: Diethyl Aluminum Hydride separated from the residue and analyzed by means of Bu Alz Tributyl Aluminum gas chronatography. The results are shown in Table 2.

TABLE 2 Alkyl Organic aluminum Titanium phosphorus Al/Ti P/Ti Pressure, Temper- Time, Butene, Pentene, Hexene, Example compound compound 1 compound ratio ratio kg./cm. g. ature, 0. hrs. g. g. 2

22 Et A1 PhTi (BuOhP 6 3 16 60 4 Trace Trace 1.2 23 EtgAl P-Bu PhTi (PhO)aP 6 2 16 60 a do do 1.0 34 BugAl PhTi PhaP 6 a 16 so 2 do do 1.0

l The titanium compound used was 1 m. mo1z30 g. of propylene was 4-methyl-2-pentene: ea. 40%. used. 2-methyl-p-pentene: ca. 11%.

1 Hexene composition: Others: ca. 29%.

4-methy1-1-pentene plus 3-methyl-1-pentene: ca. 20%. I M "a 'dwl Md p- Pr "Al: Tri-n-propyl Aluminum EXAMPLES 27.

(C H, Al: Trihexyl Aluminum 2. Titanium Compounds.

PhTi: Phenyl Titanate: Ti(OPh P-MePhTi: para-Methyl-phenyl Titanate P-Bu'PhTi:

In the same manner as described in Examples 22 24, the catalyst solution was charged into the autoclave. After the autoclave was cooled to a temperature of 0 C, the prescribed quantity of propylene was para-tertiaryButyl-phenyl Tltanate charged. The autoclave, was kept in a water bath at the P-AmPhTi: para-tert aryAmyl-ph nyl Tftanate reaction temperature for 30 minutes. When the system meta'temaryButyl'phenyl Tltfmate attained constant pressure, additional ethylene was P" P l 'y y -p y added to the system and the reaction carried out at a BILiTiI Bulyl Tllanate constant pressure for a prescribed period of time. After 4' P PY Titanale the reaction, by the same process as described in Exam- Et Ti: Ethyl Titanate ples 1 to 21, unreacted propylene, butenes, pentenes 3. Phosphorus Compounds. and hexenes were separated and analyzed by means of MePhO) P: Tricresyl Phosphite gas chromatography. The results are shown in Table 3.

' TABLE 3 Alkyl Organic aluminum Titanium phosphorus Al/Ti P/Ti Pressure Temp, Time, Butene Pentene, Hexen'e", Example compound compound 1 compound ratio ratio kgJcm. gJ 0. hr. g. g. g,

25- Etml P-Bu PhTi (EtOhP s 2 n+2 2 5.2 3.0 0.5 20 Emu P-MePhTi (Decyl-O)rP s 2 l6+2 1a 2 7.0 5.0 0.2 27 Emu P-Am'PhTi PhsP 0 2 1e+2 15 a 0.0 3.0 0.5

11 CI. Table 2. B Penteno composition: 3-methyl-l-butene, 30-40%; 2-methyl-1-hutene, 60-60%. 4 Ethylene pressure 2 kg./cm. g. added. M biota-In an alkyl aluminum compound Ni Co system: a-olefln is several percent lower in dimers produced.

(EtO) P: Triethyl phosphite EXAMPLES 28 (Mecnap Trimethyl Phosphue (Pflohp: 0 The catalyst was prepared in a 200 ml. autoclave p plf Phosphite with an electromagnetic stirrer in a nitrogen filled dry (Bunohpi Tnnfbutyl phosphfte box. 1.0 m. mol of the titanium compound shown in y h Tl'ldecyl Phosphlte Table 4 was weighed in, and calculated quantity of an h Triphenyl Phosphite n-heptane solution of the alkyl aluminum shown in )2 y p y Decyl Phosphite 55 Table 4 was added, then a calculated quantity of the or- (PhO)P(0-Laufyl)21Dilaurylphenylphosphite ganic phosphorus compound shown in Table 4 was (C H sh Trila y phosphite added. Then n-heptane was additionally added until a y h yl-hexyl) Phosphite total volume of ml. was reached. The three com- (C, H -,S) P(OPh): Phenyl-dilauryl-dithio phosphite ponent catalyst system thus obtained was ripened for 30 minutes and then ethylene was added. After the system was kept at a constant pressure, the reaction was carried out for a definite period of time. After that, the autoclave was cooled to a temperature of '60 C and the products in the reaction vessel were discharged through a trap previously cooled with a carbon dioxide methanol solution. Further, by heating the reaction solution, the low boiling substances consisting mainly of n-butene were collected in the same trap. High boiling substances consisting mainly of hexene in the reaction solution were respectively separated and analyzed by means of gas chromatography. Further, the solid polymers were washed with a hydrochloric methanol solution and dried and weighed. The results are shown 15 in Table 4.

COMPARISON EXAMPLE 3 4.

In the sameprocess as described in Examples 28 44, the results of the reaction of ethylene with a 20 catalyst consisting of alkyl aluminum and titanium compounds were obtained and are shown Table EXAMPLES 45 47 placed in a water bath maintained at the reaction tem- 3o perature and was left a prescribed period of time to complete the reaction. After this, unreacted propylene and dimers were separated from the residue and analyzed by means of gas chlomatography. The results are shown in Table 5.

EXAMPLES 48 50 In the same manner as described in Examples 28 44, the catalyst solution was charged into the autoclave. After the autoclave was cooled to a tempera ture of C, the prescribed quantity of propylene was charged. The autoclave was kept in a water bath at the reaction temperature for 30 minutes when the pressure of the system attained constancy, additional ethylene was added to the system and the reaction carried out at constant pressure for the prescribed period of time. After the reaction, by the same process as described in Examples 28 44, unreacted propylene, butenes, pentenes and hexenes were separated and analyzed by means of gas chlomatography. The results are shown in T efi- What is claimed is:

.1. A process for the dimerization or co-dimerization of an a-olefin having from two to four carbon atoms, which comprises contacting said a-olefin with a catalyst consisting of A. at least one alkyl aluminum compound selected from the group consisting of R Al and R AIH, wherein R is an alkyl radical having from two to six TABLE 4 Tim- Alkyl nium Relative aluminum com- Organic phosphorus Al/Ti P/Ti Pressure, Temp., Time, liutono-l, quantity, Polymer, Example compound pound l compound ratio ratio kgJcm. g. 0. min. g. percent gJ Blnli (MeOhP 5. 4. 0 15 60 30 21.0 99. 0 0.03 Burli (EtOhP 5. 5 4. 0 60 30 19. 0 99. 1 0. 04 Bu Ti (Pr OhP 5. 5 4.0 5 30 13. 0 98. 2 0. BmTi (Bu 0)31 0. 5 a. 0 2o 60 c1. 8 99. 5 0. 0o BulIi (2Et-hexy1-O);P 6. 0 2. 0 10 30 15. 3 98. 0 0. 10 Buril (Decy1-0);P 6.0 2. 0 30 30 45.0 99. 0 0.06 EtrTl P 6. 0 1.0 5 50 30 26. 1 99. 4 0.22 Prfili 7. 4 4.0 15 30 40. 0 98 0 0.09 PruTi 5. 5 0.5 15 60 30 21. 0 99. 0 0. 72 EtrIi 5. 0 0.5 15 30 20.0 99.1 0.15 BmTi 7. 5 3.0 15 60 30 17. 0 99. 0 0. 10 BurTi 7. 0 1. 0 15 50 30 15; 0 99. 2 0. BmTi 5. 0 0. 5 5 60 30 25.1 99. 4 0.54 BuiTi 7.0 1. 0 10 30 13'. 1 99. 4 0. 12 Bl-HTI 5. 0 1. 0 5 50 30 17. 4 94. 5 0. 94 uiTi 5.0 0.5 15 70 21. 5 98. 9 0. 20 Blla'li 7. 4 4. 0 15 60 30 30. 0 98. 2 0. Comparative EtaAl B114T1 5.0 5 50 30 15. 6 98. 6 1. 35

Example 3. Comparative EtaAl BuiTi 5. 0 20 50 30 45. 1 98. 5 2. 83

Example 4.

1 Titanium compound: 0.8-1.0 m. moi is used. Relative quantity shows the content oi l-butene in the formed n-butene.

TABLE 6 All: yl Organic aluminium 'litnnlum phosphorus All'll il'ii lrcssurc 'lom 'iimo, llutono, lcnteno, llcxcnc, Examplv compound compound 1 compound ratio ratio kgn/om. g. hr. g. g. g.'-

45 EtzAl BunTi (BuOhP 4 16 60 4 Trace. Trace. 1. 6 EtzAl Bu u'li (Ph0)aP 4 10 60 3 .do -do. 1.2 47 Et Al PrnTi Ph P 4 16 75 2 ..do d0. 1. 0

1 Titanium compound used was 1 mrn'ol, 30 g. of propylene was used 2 Hexene composition: 4-methyl-1-pentene plus S-methyl-l-pentene, ca. 20%; 4-methyl-2-pentene, ea. 40%; 2-methyi-1-pentene, ca. 11%; others, ca.

TABLE 6 Alkyl Organic aluminium Titanium phosphorus Al/Ti P/Ti Pressure Temp, Time, Butcnc, Pentenc, Hcxenc, Example compound compound 1 a compound ratio ratio kgJcin. g. C. hr. g. g 11.;

-18"... Et Al Bu rTi (EtOhP 2 16+2 75 2 5.0 2. 5 0. 5 49.. EtgAl Bu u'li (Decyl-Ohl 2 164-2 75 2 6. 5 5. 0 0. 2 50 Et;Al PrhTi PhaP 2 16+2 75 2 5. 5 3. 0 0. 5

1 Titanium compound used was 1 mmol; 30 g. of propylene was used. 2 Ethylene pressure: 2 kgJcm. added. 3 Penteuc composition: 3-methy l-butene, ca. 30-40%; 2-methyl-1-butene, ca. 50-60 7 4 Hexene composition: 4-methyl-1-pentene plus 3-methyi-1-pentene, ca. 20%; 4-methyl-2-pentene, ca. 40%; Z-methyl-l-pentenc, 11%; others, 29%.

alkyl, an aryl, an aralkyl and an alkyl-aryl radical,-

and Z is selected from the group consisting of an oxygen atom and a sulfur atom.

2. The process according to claim 1, wherein the molar ratio of the alkyl aluminum compound to the titanate ranges from 1.0 to 20.0.

3. The process according to claim 1, wherein the aolefin is ethylene.

4. The process according to claim 1, wherein the aolefin is propylene.

5. The process according to claim 1, wherein the aolefin is a mixture of ethylene and propylene.

6. The process according to claim 1, wherein the reaction temperature ranges from --10 to 150 C.

7. The process according to claim 1, wherein the reaction temperature ranges from 30 to 80 C.

8. The process according to claim 1 wherein the titanate is Ti(OAr) .9. The process according to claim 1, wherein the titanate is Ti( OR 10. The process according to claim 1 wherein the process is carried out in a solvent selected from the group consisting of aliphatic, aromatic and alicyclic hydrocarbons.

11. The process according to claim 1 wherein said organic phosphorus compound is selected from the group consisting of trimethyl phosphite, triethyl phosphite, tri-isopropyl phosphite, tributyl phosphite, tridecyl phosphite, triphenyl phosphite, trilauryl-trithio phosphite, Z-chloroethyl phosphite, phenyl-dilauryldithio phosphite, diphenyl-hydrogen phosphite, dibutyl-hydrogen phosphite, triphenyl phosphine, tricresyl phosphine and trioctyl phosphine.

12. A process according to claim 1 wherein molar ratio of said organic phosphorus compound to said titanate is in the range of 0.1 to 20.

13. A process for the dimerization or co-dimerization of an a-olefin having from two to four carbon atoms, which comprises contacting said a-olefin with a catalyst consisting essentially of A. at least one alkyl aluminum compound selected from the group consisting of R -,Al and RgAlH, wherein R is an alkyl radical having from two to six carbon atoms;

B. at least one titanate selected from the group consisting of Ti(OAr), and (TiOR') wherein Ar is an aryl radical having from six to 11 carbon atoms and R is an alkyl radical having from one to eight carbon atoms, and

C. at least one organic phosphorus compound selected from the group consisting of (RZ)(R Z )(R Z)P, R R R P and alkyl and aryl esters of said R R R P, wherein each of R, R and R is selected from the group consisting of a hydrogen atom, an alkyl, an aryl, and aralkyl and an alkyl-aryl radical, and Z is selected from the group consisting of an oxygen atom and a sulfur atom. 

2. The process according to claim 1, wherein the molar ratio of the alkyl aluminum compound to the titanate ranges from 1.0 to 20.0.
 3. The process according to claim 1, wherein the Alpha -olefin is ethylene.
 4. The process according to claim 1, wherein the Alpha -olefin is propylene.
 5. The process according to claim 1, wherein the Alpha -olefin is a mixture of ethylene and propylene.
 6. The process according to claim 1, wherein the reaction temperature ranges from -10* to 150* C.
 7. The process according to claim 1, wherein the reaction temperature ranges from 30* to 80* C.
 8. The process according to claim 1 wherein the titanate is Ti(OAr)4.
 9. The process according to claim 1, wherein the titanate is Ti(OR'')4.
 10. The process according to claim 1 wherein the process is carried out in a solvent selected from the group consisting of aliphatic, aromatic and alicyclic hydrocarbons.
 11. The process according to claim 1 wherein said organic phosphorus compound is selected from the group consisting of trimethyl phosphite, triethyl phosphite, tri-isopropyl phosphite, tributyl phosphite, tridecyl phosphite, triphenyl phosphite, trilauryl-trithio phosphite, 2-chloroethyl phosphite, phenyl-dilauryl-dithio phosphite, diphenyl-hydrogen phosphite, dibutyl-hydrogen phosphite, triphenyl phosphine, tricresyl phosphine and trioctyl phosphine.
 12. A process according to claim 1 wherein molar ratio of said organic phosphorus compound to said titanate is in the range of 0.1 to
 20. 13. A process for the dimerization or co-dimerization of an Alpha -olefin having from two to four carbon atoms, which comprises contacting said Alpha -olefin with a catalyst consisting essentially of A. at least one alkyl aluminum compound selected from the group consisting of R3Al and R2AlH, wherein R is an alkyl radical having from two to six carbon atoms; B. at least one titanate selected from the group consisting of Ti(OAr)4 and (TiOR'')4, wherein Ar is an aryl radical having from six to 11 carbon atoms and R'' is an alkyl radical having from one to eight carbon atoms, and C. at least one organic phosphorus compound selected from the group consisting of (R1Z)(R2Z)(R3Z)P, R1R2R3P and alkyl and aryl esters of said R1R2R3P, wherein each of R1, R2 and R3 is selected from the group consisting of a hydrogen atom, an alkyl, an aryl, and aralkyl and an alkyl-aryl radical, and Z is selected from the group consisting of an oxygen atom and a sulfur atom. 